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Angular differential imaging (ADI) is a speckle-suppression technique for high contrast imaging used along with coronagraphy, e.g., for attempting direct imaging of extra-solar planets. It consists of allowing a telescope to rotate in relation to the source so that different CCD pixels are recording portions of the image. The noise pattern created by the telescope can be isolated since it stays with the telescope, whereas the source image rotates. Through stacking images rotated so as to isolate each, then using subtraction, much of such noise can be removed.